GB243039A - Improvements in and relating to wireless receiving apparatus and the like - Google Patents

Abstract

243,039. Taggart, J. Scott-. June 18, 1924. Thermionic amplifiers and detectors.-In wireless receivers of the dual amplification or reflex type, the low-frequency currents are fed back by means of a resistance coupling. A tuned circuit L1, C1 is connected between the aerial A and earth E in series with the plate battery B2 and a resistance R5, of the order of 70,000 ohms., shunted by a condenser C2. The amplifier VI has its grid connected to the aerial A through a condenser C3, and its positive filament terminal earthed, a grid leak R3 being connected between the grid and the negative terminal of the filament battery B1. The plate coil L2 transfers the highfrequency output to the tuned grid circuit of a detector valve V2 fitted with the usual grid leak R4 and condenser C5. The high-frequency output coil L4 of the valve V2 reacts on the aerial coil L1, and the low-frequency output is fed by the resistance R5 into the grid circuit of the valve VI. The low-frequency output of the valve V1 is utilized in the telephones T, or is fed by resistance or transformer coupling to the grid of a third valve functioning as a low-frequency amplifier. The rectifying valve V2 mav be replaced by a crystal or other detector. A tunedanode coupling may replace the transformer coupling L2, L3, and the telephones T (or the low-frequency coupling to the third valve) may be located between the plate of the valve VI and the tuned anode circuit. Reaction may be provided between the plate circuit of the valve V2 and the plate coil of the valve V1; or between the plate circuit of the valve VI and the aerial.